Acid-sintered nanosilica coatings have been prepared by acidifying an aqueous colloidal suspension of nanometer-scale particles to a pH of less than 5, for example 2-3. Such silica nanoparticle coatings include those, for example, described in co-owned U.S. Patent Application Publication Nos. 2011/0033694 (Jing et al.) and 2010/0035039 (Jing et al.) and in co-owned International Application Publication Nos. WO 2012/064646 (Riddle et al.), WO 2011/139573 (Pett et al.), and WO 2012/047422 (Hebrink et al.). At a pH of 2-3, the particles possess little or no net charge, and can thus aggregate and fuse. Upon drying, the particles sinter at temperatures much lower than would be required without acidification. The result is a hard, porous, and hydrophilic coating that can be applied to various substrates. Dry dirt and dust exhibits reduced adhesion to nanosilica-coated surfaces relative to common glass or polymeric substrates, plus the nanosilica-coated surfaces have anti-fogging and anti-soiling properties. While acid-sintered nanosilica coatings have been shown to be acceptably stable to moisture and UV light, they do not possess sufficient impact and/or abrasion resistance for some applications.